This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to Appln. No. 199 46 921.0 filed in Germany on Sep. 30, 1999, now published as German Offenlugungsschrift DE 19946921 A1; the entire content of which is hereby incorporated by reference.
The invention relates to methods and devices for cleaning pipe conduits, and, more particularly to methods and devices for temporarily removing measuring sensors from the pipe conduits during the cleaning process.
In many applications, it is necessary to clean conduits or vessels before they are put into operation. Putting into operation may, in this case, be commissioning, during which any residues from the manufacturing process must be removed beforehand, or else recommissioning. In the latter instance, residues from prior use, for example residues of a chemical substance, often have to be removed. To clean such conduits or vessels, it is frequently expedient to blow them out with steam. Thus, for example, the water/steam circuit of a power station is also blown out, as a rule with steam, before the power station is put into operation, in order to remove residues. So that the degree of cleanliness can be measured, a metallic mirror is positioned at a suitable location in the flow. The number of particle impacts within a specific period of time is then evaluated as a measure of cleanliness.
Due to the way in which the mirror has usually been mounted hitherto, above all the operation of changing the mirror has presented problems, particularly with regard to relatively long conduit systems closed on themselves. The mirror is usually installed in the conduit or vessel at a suitable location in a nonadjustable arrangement which cannot be demounted during the blow-out operation. The conduit or vessel is subsequently blown out. For this purpose, the conduit or vessel is mostly subjected to excess pressure. Furthermore, because of the high temperatures of the steam, the conduit or vessel usually has a high temperature. So that the degree of cleanliness of the conduit or vessel can be determined after a predefined measuring time has elapsed, then, it is necessary to remove the measuring mirror from the conduit or vessel and count the particle impacts. For this purpose, the blow-out operation has hitherto had to be discontinued, in order to demount the measuring mirror from the conduit or vessel. However, it has been possible to demount the measuring mirror only after the pressure in the conduit or vessel has been discharged. Also, the conduit or vessel has first had to be cooled to an extent such that demounting work could be carried out on it. For this reason, the operation of blowing out the water/steam circuit of a power station has hitherto had to be interrupted, as a rule, for several days in total, merely in order to remove the respective measuring mirrors from the flow and/or in each case position a new measuring mirror in the flow.
The object of the invention is, therefore, to provide a device and a method, with the aid of which it is possible to position a measuring sensor in and remove it from a pressurized or flow-through conduit or a pressurized or flow-through vessel, without the pressure previously having to be discharged or the flow through the conduit or vessel having to be interrupted.
The device according to the invention for moving a measuring sensor into and out of a pressurized or flow-through conduit or a pressurized or flow-through vessel comprises a holding element for holding the measuring sensor, a guiding element for guiding the holding element and a volume element. The holding element may, in this case, be positioned in such a way that the measuring sensor held by the holding element is arranged in the interior of the volume element. Furthermore, the volume element is capable of being sealed off relative to the conduit or the vessel by means of at least one sealing-off device. Preferably, furthermore, the device also comprises a second sealing-off device which is executed preferably separately from the first sealing-off device and by means of which the volume element is capable of being sealed off relative to the surroundings.
It is thus possible for the fluid located in the volume element to be separated completely from the fluid located in the conduit or vessel. At the same time, the volume element is open to the surroundings or, in the case of the preferred version of the device with a second sealing-off device which seals off the volume element relative to the surroundings, may be opened to the surroundings. Thus, in this state, fluid exchange and consequently also pressure equalization between the fluid located in the volume element and the fluid of the surroundings may take place. It is thereby possible to remove the measuring sensor located in the volume element from the holding element or else arrange a new measuring sensor in the holding element, without this necessitating a disruption in the flow through the conduit or vessel or even a discontinuation of the throughflow operation. Furthermore, there is also no further need to equalize any overpressure or underpressure in the conduit or vessel in relation to the pressure of the surroundings in order to make it possible to change the sensor.
In principle, for the purpose of mounting or removing the measuring sensor, it is possible to leave the holding element in the guiding element and therefore mount or demount only the measuring sensor or to remove the holding element together with the measuring sensor from the guiding element in order to carry out the mounting and demounting of the measuring sensor in the demounted state.
If, in a preferred version, the second sealing-off device is also arranged according to the invention, it is thereby advantageously possible, on the one hand, to seal off the volume element relative to the surroundings and, on the other hand, to open said volume element relative to the fluid located in the conduit or vessel. In the event of a pressure difference between the surrounding pressure and the pressure in the conduit or vessel, there is in this case merely a pressure equalization of the pressure in the conduit or vessel and the pressure in the volume element, but no permanent flow through the volume element. In this state, the holding element may be moved or displaced through an introduction orifice located in the conduit or vessel, in such a way that the measuring sensor located in the holding element projects into the region of the flow or into the region of the fluid located in the conduit or vessel or else is arranged completely in the flow. Accordingly, measurement can be carried out, with the measuring sensor in this position, without disruption being caused by an inflow or an outflow of fluid through the introduction orifice of the holding element.
Thus, with the aid of the device according to the invention, it is no longer necessary to interrupt the flow through the conduit or vessel or to vent the conduit or vessel relative to the surroundings so that the measuring sensor can be introduced into or removed from the conduit or vessel. In particular, it is also possible to renew the measuring sensor, without at the same time having to interrupt the operation of blowing through the conduit or vessel. This results in enormous amounts of time being saved, as compared with the previous measurement sequence. As regards the application in which a water/steam circuit of a power station is cleaned, a time saving of up to several days can be achieved as compared with cleaning methods conventional hitherto, as result of the use of the device according to the invention.
In a preferred embodiment, the volume element is designed as a T-shaped tubular piece with at least three orifices, two orifices serving for leading the guide or the holding element and a further orifice expediently being designed as an inspection orifice for mounting or demounting and removing the measuring sensor. The two orifices serving for leading through the guide are preferably arranged in alignment with one another. In a simple version, the inspection orifice is designed as a handhole and is closed by means of a simple screwable lid. The volume element advantageously has an interspace having a diameter larger than the diameters of the orifices. As a result, the accessibility of the measuring sensor in the region of the interspace is increased and the mounting work is therefore made easier.
Preferably, the volume element is designed to be thermally insulated relative to the conduit or vessel. This is advantageous, in particular, when the fluid carried in the conduit or vessel has high temperatures. The thermal insulation, which consists, for example, of a material layer of low thermal conductivity arranged between the conduit or vessel and the volume element, prevents the material of the volume element having temperatures which are too high, in particular on its outside. High temperatures on the outside of the volume element could result in the situation where work to be carried out on the volume element by operators may be possible only after a cooling phase.
Expediently, a stop element, preferably a stop valve, is arranged, as a sealing-off device for sealing off the conduit or vessel relative to the volume element, between the conduit or vessel and the volume element. Such stop elements are known in a wide variety of versions in the prior art and are obtainable cost-effectively in the trade. Furthermore, such stop elements can be activated and regulated in a simple way either manually or electronically.
Preferably, furthermore, a vent valve communicating with the volume element is arranged. By means of this vent valve, after the volume element has been sealed off completely, it is possible in a simple way, by opening the vent valve, to equalize an overpressure or underpressure possibly present in the volume element relative to the surroundings. Particularly when a larger orifice, for example a handhold, has to be opened in the volume element for mounting or demounting the measuring sensor, it is expedient, before the handhole is opened, to achieve pressure equalization between the fluid in the volume element and the surrounding air pressure. Vent valves suitable for this purpose are known in the prior art and are obtainable in the trade.
Particularly for measuring the cleanliness of a conduit system or of a water/steam circuit of a power station, it is especially expedient to use a metallic mirror as measuring sensor. A conduit system consists, in this context, of at least one conduit or one pipe conduit and/or also of at least one vessel. The conduit system is, in this case, cleaned preferably with steam which is blown through the conduit system. The metallic mirror is, in this case, introduced into the flow in such a way that the flow strikes the mirror frontally. Particles entrained by the steam therefore strike the front side of the mirror and leave impact traces behind there. The number of impact traces within a specific measurement period is, in this case, a measure of the cleanliness of the conduit system.
In order to connect the device according to the invention to the respective conduit or respective vessel, the device expediently comprises, furthermore, a connecting element, preferably a weld-on flange. In this case, this connecting element is connected on one side directly to the conduit or vessel and on the other side advantageously to the stop element. In an expedient version, the connecting element is welded nonreleasably to the conduit or vessel, whereas the connection between the connecting element and the stop element is advantageously made by means of a flanged connection. The connection between the connecting element and the stop element is therefore releasable, so that the device according to the invention can be removed and used elsewhere after the cleaning process.
The method according to the invention for measuring the cleanliness of conduits, in particular of conduits or pipe conduits of a water/steam circuit of a power station, and/or the cleanliness of a vessel, a fluid cleaning the conduits and/or the vessel flowing through the conduits and/or the vessel, comprises the work steps listed below:
arrangement of a measuring sensor in a holding element, the holding element previously having been moved to a first position for the purpose of arranging the measuring sensor, and the first position being within a first region which is initially sealed off relative to the fluid;
preferably complete sealing-off of the first region;
connection of the first region to the fluid, so that fluid can flow out of the conduit into the region of the measuring sensor;
movement of the sensor out of the first region into a second region, the second region being located within the flowing fluid;
dwelling of the sensor in the second region for a measurement period;
after the end of the measurement period: movement of the sensor out of the second region into the first region;
sealing-off of the first region relative to the fluid;
preferably opening of the first region relative to the surroundings;
removal of the measuring sensor from the holding element and/or determination of a measurement value.
In order to carry out the method, a device according to the invention, as described above, may advantageously be used in this case.
As compared with the methods known hitherto for measuring the cleanliness of conduits, in particular of a water/steam circuit of a power station, and/or a vessel, the blowing-through of the conduit system and/or of the vessel and therefore the cleaning process do not have to be interrupted in order to carry out the method according to the invention for measuring cleanliness. This results in a marked time saving over the entire duration of the cleaning process.
The method step described last above is advantageously subdivided into the work steps of opening a vent valve to achieve pressure equalization between the pressure of the fluid in the first region and a surrounding pressure, and of subsequently opening an inspection orifice of the first region.